There is a new feature coming to DirecTV, Media Share PC.
With this feature you can stream your recorded shows from your DVR to your computer.

At this time it's in Beta & only works on the HR20-700 HD DVR & you need a good graphics card & a pretty fast processor & plenty of RAM.
I don't know what the final release will look like but right now it's only recorded shows in your play list that can be watched not a live show, you can however start a recording on your DVR & watch it in real time as you are recording it.
I've been playing with it for a couple of weeks & it's working pretty well, I can watch a show on my computer even while the girlfriend is watching another recorded show on the TV.
There is still some bugs to be worked out but I can see this being a handy feature for a lot of people.

I have my HR20 networked so it will already stream pictures, video & music from my computer through the receiver to the TV.
If your asking if you can use the computer hard drive to store recordings from the DVR the answer is no, probably a copy protection thing.

Well, that is kinda cool! I have been busy over on the dbstalk forum (http://www.dbstalk.com/showthread.php?t=129850), and, from what you say, when I place the HR20 on my network, it should see the shares on my NAS, and Twonky (if DLNA), UPnP otherwise, should be able to send stuff to the Sat box, and then to my Denon (via HDMI), and then to my Mits.

Well, that is kinda cool! I have been busy over on the dbstalk forum (http://www.dbstalk.com/showthread.php?t=129850), and, from what you say, when I place the HR20 on my network, it should see the shares on my NAS, and Twonky (if DLNA), UPnP otherwise, should be able to send stuff to the Sat box, and then to my Denon (via HDMI), and then to my Mits.

The navigation menu on the HR20 is OK?

Thanks again!

Yea the navigation menu is OK, nothing great but that's the way it's been since DirecTV manufactures all the boxes to their specs.
I always preferred the aftermarket boxes, they had much better user interfaces.

If you don't already have one you may not get a HR20, I think they are being phased out of the supply line for the HR21.
The 2 boxes are very similar but the HR21 does not have OTA antenna inputs & if you want OTA on it you'll have to get the AM21.